Ice detectors



D. w. MOORE ETAL 2,901,741

ICE DETECTORS Filed June 2, 1958 INVENTOR. DAV/D W MOORE BY WILL/AM E BLAIR AT TORNE V Aug. 25, 1959 United States Patent O ICE DETECTORS David W. Moore, Pacific Palisades, and William E. Blair, Redondo Beach, Calif., assignors to Servomechanisms, Inc., Hawthorne, Califi, a corporation of New York Application June 2, 1958, Serial No. 739,149

3 Claims. Cl. 340-234 This invention relates to ice detectors.

It is an object of this invention to provide an apparatus for continuously detecting the formation of ice.

It is a further object of this invention to provide an apparatus for detecting ice formation which is entirely mechanically operated and which does not rely upon sensitive factors which might be affected by rain or dirt contaminations, such as for example, changes in pneumatic pressures.

It is an additional object of this invention to provide an ice detector of simple mechanical construction and of repetitive reliability which can be depended upon to produce consistent and repeatable ice formation indications.

The foregoing and other objects of this invention will become apparent to those skilled in the art upon an understanding of the selected embodiment of this invention illustrated in the accompanying drawings and described in the accompanying specification when considered in the light of the appended claims.

In the drawings:

Figure 1 is a longitudinal section view through a selected embodiment of this invention and taken along the line 11 of Figure 1 and the line 1-1 of Figure 2;

Figure 2 is an end view looking toward the right in Figure l; and

Figure 3 is an end view looking toward the left in Figure 1, showing a cover plate removed for purposes of clarity.

Basically, the ice detection system of this invention comprises an alternating current motor assembly 1 which drives a small cylinder 2; an ice shaving knife edge 3 in proximity with the cylinder; and means for sensing changes in motor torque responsive to the formation of ice upon the cylinder 2.

The foregoing apparatus is supported partially within and partially without a box-like casing 5. One end of the casing 5 is closed by an integral end wall 6 provided with mounting flanges 7 and mounting holes 8 in the mounting flanges. A hearing supporting collar 9 is mounted within an offset shaped bore 10 provided in the end wall 6 and it provides a rigid support for a bearing 11 carrying one end of the motor assembly 1. A bracket 12 located at the opposite end of the casing 5 is secured to the casing and it provides a rigid support for hearing 13 carrying the opposite end of the motor assembly 1. Bearings 11 and 13 are in axial alignment with each other.

The motor assembly 1 comprises a housing 14, a gear box 15, a drive shaft 16, an end plate 17 attached to the motor housing 14, and a shaft 18 secured to the end plate. Drive shaft 16 and shaft 18 are in axial alignment with each other. Drive shaft 16 is driven from the rotor (not shown) of the motor through the gear box 15. The motor assembly 1 and the foregoing elements are cradled in bearings 11 and 13, respectively, by drive shaft 16 and by shaft 18. The cylinder 2 is secured to the outboard end of shaft 16 and the knife edge 3 is rigidly secured to the collar 9 by means of extension 19. In the selected embodiment of this invention, the knife edge 3 is sepp 2,901,741 1C Patented Aug. 25, 1959.

arated from the cylinder 2 by a distance of approximately 0.005 inch. The outboard'end of the shaft 18 is pro vided with a torque arm 20. The torque arm 20 is pinned to shaft 18 by a pin 21 and is provided with an adjustable tappet 22 which contacts the operating button 23 of a microswitch 24 securely fastened to the bearing support 12.

Leads 25 extending through a grommet 26 to the motor 1 are provided for supplying current to the motor 1, and leads 27 extendingsthrough the grommet 28 from the switch 24 are provided for transmitting information from the switch 24 to .an outside source. The open end of the frame 5 is closed by an end cover 29 which is fastened by means of screws30. H 7

By way of example, the ice detectorof the selected embodiment of this invention is mounted in an aircraft so that the cylinder 2 protrudes into an intake duct at a location where icing conditions must be detected. A source of power is applied .to the leads 25 and the shaft 16 and cylinder 2 rotate in a counterclockwise direction, viewing Figure 2. Because of the clearance between the knife edge 3 and the cylinder 2, the torque required to drive the cylinder 3 is very small, since only bearing friction within the motor and that provided by bearing 11 needs to be overcome. When icing conditions are present, ice forms upon the cylinder 2. This ice formation builds up on the cylinder 2 until the 0.005 inch gap between the cylinder 2 and the knife edge 3 is filled. When this gap has become filled with ice, the knife edge 3 starts to shave the ice and thereby increases the torque upon the motor. This increase upon the torque of the motor is reflected as an opposite torque upon the housing 14 of the motor 1, thereby tending to rotate shaft 18 in a counterclockwise direction, as viewing Figure 3. This rotates torque arm 20 in a counterclockwise direction, thereby operating the microswitch 24 through the tappet 22 and operating button 23. This microswitch, through loads 27, is connected to external circuitry (not shown), which is thereby switched by the icing condition.

So long as the ice continues to form, the knife '3 will continue to shave ice upon the cylinder 2 and the motor drive torque transmitted through the housing of the motor and torque arm 20 will be high enough to maintain the microswitch 24 in a closed position. When ice stops forming, the knife edge 3 takes a final cut and the detector frees itself and returns to a no ice indication.

It will be observed that the foregoing detector does not operate cyclically, but that it operates continuously. As such, it requires no heater and is self-clearing after the icing conditions have ceased.

This detector is exceedingly rugged in design and has unusual reliability in the field. The resulting unit affords an extremely simple and direct method of sensing the formation of ice. It is free of calibration problems, either initially or throughout the life of the detector.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitation should be understood therefrom, for modifications will be obvious to those skilled in the Accordingly, the scope of the invention is defined in the appended claims.

We claim:

1. Ice detecting apparatus including: frame means; bearing means carried by said frame means; torque-producing means having an active element and a reactive element; an active shaft being connected to the active element of said torque-producing means; a reactive shaft being connected to the reactive element of said torqueproducing means; said shafts being in axial alignment and being carried by said bearing means; a cylinder exposed to possible ice-forming atmosphere and mounted upon said active shaft; an ice-shaving knife edge carried by said frame "and arranged in proximity with said cylinder; a torque arm carried by said reactive shaft; signalling means operable in response to reactive forces transmitted by said torque arm for indicating astate of torque existing between the active element and the reactive element of said torque-produoing pieans as initiated by the formation .of ice upon said cylinder. I

.2. .Ice detecting apparatus including: frame means; bearing means carried by said frame means; a rotary motor having an active element and a reactive element; an active shaft being connected to the active element of said rotary motor; and a reactive shaft being connected to the reactive element of said rotary motor; said shafts being in axial alignment and being carried by said beara ing means; a cylinder exposed to possible ice-forming atmosphere and mounted upon said active shafflan iceshaving knife edge carried by said frame and arranged in proximity with said cylinder; a torque arm carried by said reactive shaft; a limit switch operable in response 3. Ice detecting apparatus including: frame means, bearing means carried by said frame means; an electric motor having a rotor and a stator; an active shaft being connected to the rotor of said electric motor; and a reactive shaft being connected to the stator of said electric motor; said shafts being in axial alignment and being carried by said bearing means; a cylinder exposed to possible ice-forming atmosphere and mounted upon said active shaft; an ice-shaving knife edge carried by said frame and arranged in proximity with said cylinder; a torque arm carried by said reactive shaft; signalling means operable in response to reactive forces transmitted by said torque arm for indicating a state of torque to reactive forces transmitted by said torque arm for 20 indicating a state of torque existing between the active element and the reactive element of said rotary motor as initiated by the formation of ice upon said cylinder.

existing between the rotor and the stator of said electric motor as initiated by the formation of ice upon said cylinder.

Idrac Jan. 17,1950 Vonnequt et al. Feb. .12, 1952 

